1. Field of the Invention
The present invention relates to a hybrid integrated optical module which integrates a first waveguide device having a semiconductor waveguide and is mounted on a first substrate, and a second waveguide device.
2. Description of the Related Art
Along with the spread and the progress of an optical communication network, an optical component to be used in an optical communication system has been progressing to have a high functionality. The optical component includes an active optical component to emit or receive signal light, a passive optical component to branch/combine or to de-multiplex/multiplex the signal light, an optical fiber used for a signal light transmission line, and the like, and the need of a high functionality and a low cost is increased for each of the optical components. Among them, the main active optical components is a semiconductor material based device such as a semiconductor laser element and a semiconductor light receiving element, and technology development is being promoted for this device. The active optical component based on the semiconductor material has an advantage of realizing an optical amplification function, a high speed operation, and a compact integration. Meanwhile, for the passive optical component, a planar lightwave circuit (PLC) having an optical waveguide based on silica-based material is available as a product. The PLC has an advantage of realizing a low-loss optical waveguide without polarization dependence.
While each of the active optical component and the passive optical component has been improved so far in the performance thereof as a single component, the need of a highly functional optical component having both of the above advantages is increasing along with the higher level need caused by the progress of the optical communication system. Accordingly, development is being promoted for a hybrid integrated optical module which combines the active optical component such as the semiconductor laser element and the PLC.
Japanese Patent Application Laid-Open Publication No. 2007-133011 discloses an optical module provided with a substrate, an optical waveguide and an optical element which are disposed on the substrate and optically coupled with each other, and a transformable stage which supports the optical element and changes the height thereof according to a load. By applying the load in the height direction of the transformable stage to adjust the height thereof, the height of the optical element supported by the transformable stage is adjusted.
Further, a hybrid integrated optical module optically combining different kinds of waveguide is disclosed in a technique disclosed by Japanese Patent Application Laid-Open Publication No. 2000-275480, for example. This conventional technique optically couples an optical waveguide end portion of an optical element to an optical waveguide end portion of an optical waveguide substrate, so as to cause both of the waveguides to be inclined obliquely against each other, in a hybrid integrated optical module mounting the optical waveguide substrate and the optical element on an optical component mounting substrate.
Meanwhile, in the conventional technique of above Japanese Patent Application Laid-Open Publication No. 2007-133011, a position shift of the optical element in the height direction (Y direction) can be adjusted but nothing is described about position alignment of the optical element in the horizontal direction (X direction) and distance adjustment in the Z direction which adjusts the distance between the optical waveguide and the light-emitting element to a certain distance (Z direction distance). Further, the conventional technique of above Japanese Patent Application Laid-Open Publication No. 2000-275480 performs passive alignment by using respective alignment marks provided to the optical component mounting substrate, the optical element, and the optical waveguide substrate. However, for realizing an optical module having a high coupling efficiency by suppressing a connection loss between the waveguides, it is preferable to perform active alignment including gap adjustment so as to have a certain optimal distance (gap) between the waveguides.
Further, when, for optically coupling the respective waveguides of a semiconductor device and a silica-based PLC device, the gap between the waveguides is adjusted from a zero point where both devices contact each other at the respective end faces, there arises a problem that the shape of the end face of the semiconductor device affects the gap adjustment between the waveguides in a configuration in which the semiconductor device is mounted on an optical bench.